This invention relates to a card-shaped data carrier with a thermoreversible layer.
Identification and authorization cards which are increasingly used are smart cards permitting the card owner to utilize a great variety of services, e.g. means of transport such as ski lifts, means of local transport, rental cars, sports facilities, car parks, public telephones, etc. The chip usually stores a credit balance to which a corresponding amount is debited with a read-write device upon utilization of the service, for example upon entry. In order to make the available card balance visible anytime, it is known to provide a partial area of the card with a thermoreversible layer on which a thermal printhead connected to the read-write device records the particular card balance. The data recorded on the thermoreversible layer with the thermal printhead are opaque, or transparent if the layer is opaque. In order to make them more visible the thermoreversible layer is applied to a background layer which is dark or has metallic luster (compare e.g. EP-A-0 405 054 and WO 96/11451).
Further, there is an authorization card on the market which has a thermoreversible color layer on a white carrier film and a protective layer on the thermoreversible color layer. The thermoreversible layer of the known authorization card is writable with the thermal printhead in visible color, e.g. blue.
Identification and authorization cards have in addition permanent data pictures, for example the logo of the card issuer, advertising and the like. For this purpose, a printed layer covering the greatest part of the card except for a field for thermoreversible recording is applied to the thermoreversible layer or its protective layer in the known authorization card.
U.S. Pat. No. 5,719,850 discloses a card-shaped optical storage medium which has an optical layer for recording and reading data and a printed layer under the optical layer. In the printed layer, a partial area is formed as a thermoreversible layer in order to render for example the remaining storage capacity of the optical layer visible. The thermoreversible field is written with a light beam through the optical layer.
Smart cards are being used more and more as multifunctional cards. That is, one card should permit a plurality of different entitlements. For example, one and the same authorization card can be designed as an annual ski pass for one ski area and a point ticket for other ski areas, or as a point ticket for a ski area and a point ticket for an indoor swimming pool, and at the same time as a time-limited authorization card for a means of local transport. In order to permit the particular credit balances, different periods of validity and the like to be recorded visibly on the thermoreversible layer for the individual entitlements of such a multifunctional card, an accordingly large area must be provided on the card.
The object of the invention is therefore to provide a card-shaped data carrier, in particular an identification and/or authorization card, with a thermoreversible layer which has a large-area thermoreversible recording of a large amount of data and/or pictures without the need to reduce the area for the permanent data and pictures of the card or to enlarge the card.
The card-shaped data carrier of this invention has a carrier layer to which a printed layer is applied, preferably all-over. A thermoreversible layer, which is formed as a transparent film, is applied preferably all-over to the printed layer.
The carrier layer may consist of a thermoplastic resin as is customarily used for plastic cards, e.g. PET (polyethylene terephthalate) or PVC (polyvinyl chloride), polyethylene or the like.
The printed layer, which is applied to the carrier layer for example by screen printing or another printing process, bears the permanent (nonerasable) data and pictures of the card. These may involve e.g. the logo of the card issuer, advertising or, in a ski card, a general map of the particular ski area. Since the total card surface is available if necessary, the card may be provided with a maximum of such permanently applied information.
The thermoreversible layer is provided with the erasable data and pictures. The thermoreversible layer of the inventive data carrier, which is formed as a transparent film, preferably consists of a transparent carrier film with a thermoreversible color layer applied thereto and a protective layer applied to the thermoreversible color layer. The transparent film forming the thermoreversible layer thus has a structure which, apart from the printed layer, corresponds substantially to the structure of the authorization card described at the outset, except that the carrier film is of transparent design while it is white in the authorization card described at the outset.
The transparent thermoreversible film may have e.g. a thickness of 10 to 50 microns, and the carrier film of the transparent thermoreversible film may be e.g. a PET film. The visible, non-white, color of the thermoreversible color layer which arises during recording with the thermal printhead may be a blue color, as in the known authorization card described at the outset.
Writing in visible color and erasing the data and/or pictures on the thermoreversible film may be effected in different ways. Thus, the thermoreversible film or layer may be writable with data and/or pictures in visible color with the thermal head at a first temperature, said data and/or pictures being erased through transition to a transparent state at a second higher temperature. The first temperature, i.e. the temperature at which the thermoreversible color layer changes from transparent to visible or blue, may be for example 70 to 90xc2x0 as in the known authorization card described, while the second temperature at which the visible or blue color changes back to the transparent state for erasing the recorded data and pictures may be for example 100 to 130xc2x0 C. While recording on the thermoreversible layer is effected with the thermal printhead, an erase bar or roller may be provided for erasure.
However, it is not necessary that two temperatures be applied, one for writing visible color and a second higher temperature for erasure. Rather, one can use the same temperature for writing and erasing, exploiting different cooling times, i.e. fast cooling for writing and slow cooling for erasing. That is, if the thermoreversible layer is cooled quickly, visible color occurs at the place heated with the thermal printhead, while the thermoreversible layer passes to a transparent state upon slow cooling after heating with the thermal printhead.
The inventive data carrier may be provided on one or both sides with a carrier layer with a printed layer and a transparent thermoreversible film applied to the printed layer.
The data and pictures recorded on the thermoreversible layer may be e.g. the name of the card owner or similar personalization data, a photo of the card owner, the period of validity of the card, data about points or another kind of credit balance or the like.
The permanent data and pictures borne by the printed layer of the inventive data carrier and the data and pictures recorded on the thermoreversible layer may be coordinated with each other such that in the area of the data and pictures recorded on the thermoreversible layer with the thermal printhead the printed layer forms a background contrasting therewith. This can be effected for example by lightening the printed layer in the area where data and pictures are recorded on the thermoreversible layer, e.g. in the area of the printed layer where the photo of the card owner is recorded on the thermoreversible layer.
The printed layer may in addition be provided in the area of the thermoreversibly recorded data and pictures with security features, for example color patterns or effects, UV-reflecting characters, holograms and the like, as are used for forgery-proofness in bank notes and papers of value in order to render unauthorized manipulation on the transparent, thermoreversible film visible.
The transparent thermoreversible film of the inventive data carrier at the same time forms excellent mechanical, thermal and chemical protection of the printed layer and protection from UV radiation.
The inventive data carrier is preferably provided with a chip and/or a magnetic stripe on which the data recorded on the thermoreversible layer and further data are stored. The chip has a nonvolatile, rewritable memory. The data carrier may have a contact-type and/or a contactless-type chip, for example a contactless chip for means of transport, such as ski lifts or local trains, and a contact-type chip, for example for access entitlement to a hotel room. The authorization card may be a check card, credit card or telephone card or an access entitlement card. The entitlement may be a personal entitlement, event-dependent and/or value-dependent. It may also be an identity card or driver""s license e.g. with a limited period of validity. This permits e.g. a change of address to be recorded on the thermoreversible layer without any need to produce a new card.